The structure of calmodulin and its specific interaction with several proteins will be examined, using a range of physical techniques. The molecular dynamics of calmodulin will be studied by measurements of the time decay of fluorescence anisotropy, as well as static anisotropy measurements, employing specifically located fluorescent probes. Particular attention will be paid to the effects of temperature and complex formation. The interaction of calmodulin with polypeptide hormones, troponin I, and myosin light chain kinase will be studied in detail. Radiationless energy transfer will be employed to investigate the spatial organization of complexes of calmodulin with other proteins.